DateUtils工具类

傷城~ 2022-05-27 06:46 234阅读 0赞

class DateUtils {
    
        private static Map<String, ThreadLocal<SimpleDateFormat>> sdfMap = new HashMap<String, ThreadLocal<SimpleDateFormat>>();
        private static final Object lockObj = new Object();
    
        /** * 毫秒转天 */
        public static int MILLISECOND_TURN_DAYS = 1000 * 3600 * 24;
    
        private static SimpleDateFormat getSdf(final String pattern) {
            ThreadLocal<SimpleDateFormat> simpleDateFormat = sdfMap.get(pattern);
            // 此处的双重判断和同步是为了防止sdfMap这个单例被多次put重复的sdf
            if (simpleDateFormat == null) {
                synchronized (lockObj) {
                    simpleDateFormat = sdfMap.get(pattern);
                    if (simpleDateFormat == null) {
                        simpleDateFormat = new ThreadLocal<SimpleDateFormat>() {
                            @Override
                            protected SimpleDateFormat initialValue() {
                                return new SimpleDateFormat(pattern);
                            }
                        };
                        sdfMap.put(pattern, simpleDateFormat);
                    }
                }
            }
            return simpleDateFormat.get();
        }
    
        /** * * @Title: format * @Description: 把日期格式化为指定格式 * @param date * 要格式化的日期 * @param pattern * 日期格式字符串 * @return 格式化之后的日期字符串 */
        public static String format(Date date, String pattern) {
            return getSdf(pattern).format(date);
        }
        /** * * @Title: getContinuousDates * @Description: 获取连续的日期 * @param startTime * 开始日期 * @param endTime * 结束日期 * @return 日期列表 */
        public static List<String> getContinuousDates(Date startTime, Date endTime) {
            int days = getDaysBetween(startTime, endTime);
            List<String> list = new ArrayList<String>();
            list.add(format(endTime, "yyyy-MM-dd"));
            Calendar cal = Calendar.getInstance();
            // 使用给定的 Date 设置此 Calendar 的时间
            cal.setTime(endTime);
            while (days > 0) {
                // 根据日历的规则，为给定的日历字段添加或减去指定的时间量
                cal.add(Calendar.DAY_OF_MONTH, -1);
                list.add(format(cal.getTime(), "yyyy-MM-dd"));
                days--;
            }
            return list;
        }
    
        /** * * @Title: getDaysBetween * @Description: 获取两个时间的天数差 * @param early * 早的时间 * @param late * 晚的时间 * @return 天数 */
        public static int getDaysBetween(Date early, Date late) {
            Calendar calendarEarly = Calendar.getInstance();
            Calendar calendarLate = Calendar.getInstance();
            calendarEarly.setTime(early);
            calendarLate.setTime(late);
            // 设置时间为0时
            calendarEarly.set(Calendar.HOUR_OF_DAY, 0);
            calendarEarly.set(Calendar.MINUTE, 0);
            calendarEarly.set(Calendar.SECOND, 0);
            calendarLate.set(Calendar.HOUR_OF_DAY, 0);
            calendarLate.set(Calendar.MINUTE, 0);
            calendarLate.set(Calendar.SECOND, 0);
            // 得到两个日期相差的天数
            int number = (int) (calendarLate.getTime().getTime() / MILLISECOND_TURN_DAYS
                    - calendarEarly.getTime().getTime() / MILLISECOND_TURN_DAYS);
            return number;
        }
    }